Assad mistaken on beating oppn - Clinton

US Secretary of State Hillary Clinton says Syrian President Bashar al-Assad would be 'mistaken' if he thinks he can defeat the opposition against him.

'If Assad continues as he has to fail to end the violence, ... then it is unlikely he is going to ever agree' to implement the peace plan he agreed to with UN-Arab League envoy Kofi Annan, Clinton told a news conference on Sunday.

'Because it's a clear signal that he wants wait to see whether he has totally suppressed the opposition,' Clinton said. 'I think he would be mistaken to believe that.

'My reading is that the opposition is gaining in intensity, not losing it,' Clinton said.

Clinton was speaking in Istanbul where she was attending a 'Friends of Syria' meeting at which Western and Arab countries held talks on pressuring Damascus to implement a peace plan by UN and Arab League envoy Kofi Annan.

The delegates recognised the opposition Syrian National Council as the 'legitimate representative' of all Syrians.

They also urged the United Nations to act to stop the violence, but steered clear of backing opposition appeals for arms to fight the regime clampdown.

In a final declaration, the conference urged Syria mediator Kofi Annan 'to determine a timeline for next steps, including a return to the UN Security Council, if the killing continues'.

It added: 'The regime will be judged by its deeds rather than its promises. The window of opportunity for the regime to implement its commitments to joint special envoy Annan is not open-ended.'

The gathering brought together the Arab League and countries such as the United States, France and Germany.

Assad on Tuesday said he accepted the plan proposed by Annan, but hasn't stopped the shelling of opposition strongholds.

The six-point peace plan calls for an end to violence, a daily two-hour humanitarian ceasefire and access to all areas affected by fighting, as well as an inclusive Syrian-led political process, the right to demonstrate, and th! e releas e of people detained arbitrarily.

The Istanbul gathering, which followed one in Tunis late in February, came as fighting on the ground killed more people and Damascus said it had no immediate plans to pull back its forces.

Conference host Turkey warned the world would have no choice but to recognise Syrians' right to take up arms if the UN fails to act.

'If the United Nations Security Council refrains from taking on the responsibility, the international community will have no choice but to accept Syrians' right to self-defence,' Prime Minister Recep Tayyip Erdogan said as he opened the conference.

Ahead of the gathering, Assad's regime declared victory over rebels and again voiced support for Annan's plan, but kept up its shelling of rebel positions and said it had no plans to immediately withdraw troops.

At least 40 people were killed on Sunday, among them 15 members of the security forces who died in firefights across the country, the Syrian Observatory for Human Rights said.

Assad's deadly crackdown on opponents has left more than 9000 people dead since the uprising began in March last year, according to the UN.

The Friends of Syria meeting on Sunday recognised the opposition Syrian National Council as the 'legitimate representative' of all Syrians and the 'leading interlocutor for the opposition with the international community'.

The SNC on Saturday renewed calls for arming rebels, but the final statement of the Istanbul conference did not make any reference to the pleas.

An Arab League summit in Baghdad this week rejected the option of supplying arms to either side in the conflict, though members Saudi Arabia and Qatar openly called for arming the anti-Assad movement. The US has ruled out arming the rebels.

As the Istanbul conference was under way, Syria's neighbour, Iraq, said Assad's regime will not fall and any attempts to overthrow it by force will aggravate the crisis in the region.

Damascus blasted Sunday's meeting.